Messages in this thread | | | Date | Thu, 24 Sep 2015 10:54:36 -0400 | From | Luiz Capitulino <> | Subject | Re: [PATCH 3/3] sched: add_nr_running(): drop tick_nohz_full_cpu() check |
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On Thu, 24 Sep 2015 16:44:18 +0200 Frederic Weisbecker <fweisbec@gmail.com> wrote:
> On Thu, Sep 10, 2015 at 03:58:27PM -0400, Luiz Capitulino wrote: > > tick_nohz_full_kick_cpu() performs the same check. > > > > Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> > > --- > > kernel/sched/sched.h | 20 +++++++++----------- > > 1 file changed, 9 insertions(+), 11 deletions(-) > > > > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > > index 68cda11..102eb18 100644 > > --- a/kernel/sched/sched.h > > +++ b/kernel/sched/sched.h > > @@ -1323,17 +1323,15 @@ static inline void add_nr_running(struct rq *rq, unsigned count) > > #endif > > > > #ifdef CONFIG_NO_HZ_FULL > > - if (tick_nohz_full_cpu(rq->cpu)) { > > - /* > > - * Tick is needed if more than one task runs on a CPU. > > - * Send the target an IPI to kick it out of nohz mode. > > - * > > - * We assume that IPI implies full memory barrier and the > > - * new value of rq->nr_running is visible on reception > > - * from the target. > > - */ > > - tick_nohz_full_kick_cpu(rq->cpu); > > - } > > + /* > > + * Tick is needed if more than one task runs on a CPU. > > + * Send the target an IPI to kick it out of nohz mode. > > + * > > + * We assume that IPI implies full memory barrier and the > > + * new value of rq->nr_running is visible on reception > > + * from the target. > > + */ > > + tick_nohz_full_kick_cpu(rq->cpu); > > Nope, we want to keep this because tick_nohz_full_cpu() does a static key check. > Most users don't care about nohz_full and I really want to keep nohz full off case > overhead to the bare minimum.
Makes sense.
> > Thanks. > > > #endif > > } > > } > > -- > > 2.1.0 > > >
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